package com.mo.config;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

/**
 * @apiNote web配置
 * @author lidong
 * @since 2020/07/04
 */
@Component
public class WebConfig implements WebMvcConfigurer {
    /**
     * 使用fastjson代替jackson
     *
     * @param converters
     */
    @Override
    public void configureMessageConverters(List <HttpMessageConverter <?>> converters) {
        for (int i = converters.size() - 1; i >= 0; i--) {
            if (converters.get(i) instanceof MappingJackson2HttpMessageConverter) {
                converters.remove(i);
            }
        }
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        //自定义fastjson配置
        FastJsonConfig config = new FastJsonConfig();
        config.setSerializerFeatures(
                SerializerFeature.PrettyFormat,
                // 是否输出值为null的字段,默认为false
                SerializerFeature.WriteMapNullValue,
                // 将Collection类型字段的字段空值输出为[]
                SerializerFeature.WriteNullListAsEmpty,
                // 将字符串类型字段的空值输出为空字符串
                SerializerFeature.WriteNullStringAsEmpty,
                // 将数值类型字段的空值输出为0
                SerializerFeature.WriteNullNumberAsZero,
                // 禁用循环引用
                SerializerFeature.WriteDateUseDateFormat, SerializerFeature.DisableCircularReferenceDetect
        );
        fastJsonHttpMessageConverter.setFastJsonConfig(config);
        // 添加支持的MediaTypes;不添加时默认为*/*,也就是默认支持全部
        // 但是MappingJackson2HttpMessageConverter里面支持的MediaTypes为application/json
        // 参考它的做法, fastjson也只添加application/json的MediaType
        List <MediaType> fastMediaTypes = new ArrayList <>();
        fastMediaTypes.add(MediaType.APPLICATION_JSON);
        fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
        fastJsonHttpMessageConverter.setDefaultCharset(StandardCharsets.UTF_8);
        converters.add(0, fastJsonHttpMessageConverter);
    }
}